Nowadays, a user of a device for reproducing audio or audiovisual documents can obtain them in various ways. If the document is audiovisual, it may originate from audiovisual stations accessible with the aid of a television receiver. These stations transmit audiovisual documents that can be recorded on a medium such as a magnetic cassette or a hard disk integrated with the receiver. If the document is audio, it may originate from a CD, from a digital network and be downloaded in compressed form, in MP3 format for example. In all cases, the document is received and recorded in digital form. Once the document has been recorded, the user can select it with the aid of a guide which displays an identifier of each document, and can run the reproduction.
If the reading medium is defective or if reception is not good, the device will have problems in reproducing the document recorded in this medium. If the audiovisual content is in digital form, the document is made up of digital data packets interlinked by chaining. During reproduction, the device reads all the packets and monitors the integrity of their contents; those that have not undergone any impairment will be read correctly whereas the others will be reproduced by incoherent signals. According to the reading software, reproduction may be interrupted, or loop back to a sequence which is repeated indefinitely until the user intervenes.
It is easily noted that the presence of impaired data seriously hinders reproduction and requires the intervention of a user when the device reads a defective sector.
Certain systems may read in advance a sequence of a document recorded on a medium and store it temporarily in an electronic circuit. The system monitors the integrity of the data and in the event of a defect, executes a new reading of a sequence of the medium. If the data read are still incorrect, the system reproduces incoherent signals for a few seconds and passes automatically to another sequence. In this way, the user is immediately aware of the defect, he thus knows that the medium is defective or that the data recorded are not correct. Such systems are found, in particular in a personal CD player.
Such systems do not require user interventions but have the drawback of needlessly reading impaired data. Moreover, when the impairment is definitive, the sectors possessing impaired data needlessly occupy memory room.
The present invention makes it possible at one and the same time to warn the user that the document currently being read exhibits impaired sectors and optimizes the memory room occupied by the document.